fix Issue 11401 - ElementType returns constructor instead of type

1. For `exp.member`, compiler always try to resolve property/optional parenthesis on `exp`. so use `front.init`.
2. Built-in `init` property always returns rvalue, so `front.init` won't invoke postblit.
Merge pull request #1681 from 9rnsr/fix11401

[REG2.065a] Issue 11401 - ElementType returns constructor instead of type